PortMidi - Cross-Platform MIDI IO

This is the canonical release of PortMidi.

See other repositories within PortMidi for related code and bindings (although currently, not much is here).

Full C API documentation is here.

Compiling and Using PortMidi

Use CMake (or ccmake) to create a Makefile for Linux/BSD or a project file for Xcode or MS Visual Studio. Use make or an IDE to compile:

sudo apt install libasound2-dev  # on Linux, you need ALSA
cd portmidi  # start in the top-level portmidi directory
ccmake .     # set any options interactively, type c to configure
             # type g to generate a Makefile or IDE project
             # type q to quit
             # (alternatively, run the CMake GUI and use
             #  Configure and Generate buttons to build IDE project)
make         # compile sources and build PortMidi library
             # (alternatively, open project file with your IDE)
sudo make install  # if you want to install to your system

Installation

My advice is to build PortMidi and statically link it to your application. This gives you more control over versions. However, installing PortMidi to your system is preferred by some, and the following should do it:

cmake .
make
sudo make install

Language Bindings

Here is a guide to some other projects using PortMidi. There is not much coordination, so let us know if there are better or alternative bindings for these and other languages:

• Python: Various libraries and packages exist; search and ye shall find.
• SML
• OCaml
• Haskell
• Erlang
• Julia
• C#
• Rust
• Go
• Odin
• Serpent - a real-time Python-like language has PortMidi built-in, a MIDI-timestamp-aware scheduler, and GUI support for device selection.
• Pd (Pure Data) uses PortMidi.

What's New?

(Not so new, but significant:) Support for the PmDefaults program, which enabled a graphical interface to select default MIDI devices, has been removed for lack of interest. This allowed us to also remove C code to read and parse Java preference files on various systems, simplifying the library. PmDefaults allowed simple command-line programs to use Pm_DefaultInputDeviceID() and Pm_DefaultOutputDeviceID() rather than creating device selection interfaces. Now, you should either pass devices on the command line or create your own selection interface when building a GUI application. (See pm_tests for examples.) Pm_DefaultInputDeviceID() and Pm_DefaultOutputDeviceID() now return a valid device if possible, but they may not actually reflect any user preference.

Haiku support in a minimal implementation. See TODO's in source.

sndio is also minimally supported, allowing basic PortMidi functions in OpenBSD, FreeBSD, and NetBSD by setting USE_SNDIO for CMake, but not delayed/timestamped output and virtual devices.

Other Repositories

PortMidi used to be part of the PortMedia suite, but this repo has been reduced to mostly just C/C++ code for PortMidi. You will find some other repositories in this PortMidi project set up for language bindings (volunteers and contributors are invited!). Other code removed from previous releases of PortMedia include:

PortSMF

A Standard MIDI File (SMF) (and more) library is in the portsmf repository.

PortSMF is a library for reading/writing/editing Standard MIDI Files. It is actually much more, with a general representation of events and updates with properties consisting of attributes and typed values. Familiar properties of pitch, time, duration, and channel are built into events and updates to make them faster to access and more compact.

To my knowledge, PortSMF has the most complete and useful handling of MIDI tempo tracks. E.g., you can edit notes according to either beat or time, and you can edit tempo tracks, for example, flattening the tempo while preserving the beat alignment, preserving the real time while changing the tempo or stretching the tempo over some interval.

In addition to Standard MIDI Files, PortSMF supports an ASCII representation called Allegro. PortSMF and Allegro are used for Audacity Note Tracks.

scorealign

Scorealign used to be part of the PortMedia suite. It is now at the scorealign repository.

Scorealign aligns audio-to-audio, audio-to-MIDI or MIDI-to-MIDI using dynamic time warping (DTW) of a computed chromagram representation. There are some added smoothing tricks to improve performance. This library is written in C and runs substantially faster than most other implementations, especially those written in MATLAB, due to the core DTW algorithm. Users should be warned that while chromagrams are robust features for alignment, they achieve robustness by operating at fairly high granularity, e.g., durations of around 100ms, which limits time precision. Other more recent algorithms can doubtless do better, but be cautious of claims, since it all depends on what assumptions you can make about the music.